At the beginning of the P-3 Update IV program, EMC personnel established
their requirements to control the length of pigtails and exposed wires Wiring
design and manufacturing personnel eventually chose to use metallized polymer
boots in place of E3 connector backshells The
boots were to terminate overall shields peripherally, shield the exposed
wires, and provide a bond to the connector body Figure 5-4 shows the polymer
boots on a power supply under test

Several combined circumstances defeated good connector and termination
practice:

First, the requested control on pigtail and exposed wire length was never
communicated as a requirement in manufacturing drawings

Customer concerns about the maintainability of the boots caused the program
to consider alternatives. While inspecting one booted termination, EMC personnel
found a pigtail longer than sixteen inches (folded) and exposed wire in excess
of eight inches Wiring and shop personnel had thought the boot an adequate
shield and permitted long pigtails and exposed wires to make future rework
easier

Ultimately, EMC personnel judged the boots and
terminations to be inadequate, not maintainable and impossible to inspect They
proceeded to rework all cables using conventional connectors and backshells
The length of pigtails and exposed wire was controlled by manufacturing
drawings Subsequent analysis and testing suggests that reworked cables afford
shielding superior to that of the original design Figure 5-5 shows the
finished cable assemblies connected to the power supplies onboard the
aircraft. While the use of the boots may have been suitable as an EMI
termination in some applications, it did not work out in this specific
case